But the good news is, most playground accidents happen because of the same hazards, and if you know what they are, you can avoid them.

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Summer Safety: Protect Your Kids at the Playground

There's a difference between a risk and a hazard.

We want our kids to take healthy risks on the playground because that's how they grow physically and mentally, but we need to eliminate all the most common hazards, so when they're taking those risks, there's less chance they'll get hurt.

The hazards can be invisible to a parent's untrained eye and a child's untrained body.

The Foley family of Brooklyn, New York, found that out the hard way when then 5-year-old Kira slipped on a hard metal dome play structure at a new park, breaking her nose and knocking out a tooth.

"They should be removed," said Dad Robert Foley. "While aesthetically, they look extremely nice, at the end of the day, I think they could have done a much better job at making them kid-friendly."

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Summer Safety: Avoid Lawnmower Dangers

We asked Bill Foelsch, a certified playground safety inspector and director of parks and recreation for Morris Township, N.J., to open our eyes to the most critical dangers.

First up, improper surfacing. Wood chips are the most common cushioning surface for falls and they work well, but they need to be at least 9 inches deep.

Protective fall zones are supposed to extend out from the equipment in every direction so that when kids try to climb the poles or jump off moving swings, they're protected.

"Children will play on any piece of play equipment the correct way, and when they're tired of that they'll try to invent their own new game," Foelsch said.

Lack of maintenance is the second hazard. At the playground we went to, Foelsch pointed out how the hooks holding up the swings had rusted, so they were not nearly as thick as they used to be.

"As the swing goes out, the chain breaks away and then we have an injury by something the child couldn't even see," he said.

Next up, pinch points that can crush a child's fingers.

If one child sticks his fingers into sections of the playground like a hanging bridge and another walks on it, the child's fingers can get pinched.

Head entrapment is one of the most serious -- and unexpected -- hazards caused by improper openings in playground equipment.

Playground inspectors use a smaller probe to see if a child's torso will fit into an opening and then a larger one to see if their heads will be trapped.

More Playground Dangers

Inadequate guardrails are another concern. The playground we visited had a climbing structure with a big open gap on one side and a piece of wood on the other that kids would be tempted to use as a balance beam.

And finally, entanglement hazards. The slide and platform at the playground we visited were not up to code because the space between them created a dangerous corner where kids' clothing could get caught, strangling them.

"These things really happen," Foelsch said. "Now, fortunately they don't happen every day in the country. However, every year there are five or six deaths by strangulation."

By contrast, state-of-the-art, safe playgrounds, like the one built by the nonprofit group KaBoom! at Latin American Montessori Bilingual school in Washington, DC, are designed not just for what adults think kids will do, but for what kids really will do.

The same rules apply to home playgrounds.

In fact, more children get hurt on home playgrounds than public playgrounds, because park and recreation departments hear about proper safety practices, whereas parents often don't.

Playground equipment is often attached using 's' hooks. If you can slide a dime between the opening, it is too wide -- another entanglement hazard. Kids clothing -- a neckline or a hood -- can get stuck on this open s-hook and strangle them.

Web Extra: The Rest of the 'Dirty Dozen' Playground Dangers

The National Playground Safety Institute developed a list of 12 "Dirty Dozen" hazards that parents should look out for. I've covered a few so far in my report, but here are the rest.

Improper Protective Surfacing

As we already said, improper protective surfacing can be a big hazard for kids. The following are unacceptable surfaces as determined by the NPSI:

One of the best ways to keep your kids safe is to make sure somebody is keeping an eye on them.

"Young children are constantly challenging their own abilities, often not being able to recognize potential hazards," the NPSI said. "It is estimated that over 40 percent of all playground injuries are directly related to lack of supervision."

Age-Inappropriate Activities

Safe play equipment is different for a 3-year-old than a 12-year-old. The NPSI recommends separating play areas for preschoolers (age 2 to 5) from school-age kids (age 5 to 12).

Sharp Edges

Give the playground equipment a look before your kid goes nuts on it. Keep an eye out for sharp edges or points that could cut skin.

Equipment Not Recommended for Public Playgrounds

Sometimes it's just a matter of playing on the wrong equipment. The U.S. Consumer Product Safety Commission recommends the following equipment not be used on playgrounds:

Heavy swings such as animal figure swings Multiple occupancy/glider-type Swings Free-swinging ropes that may fray or form a loop Swinging exercise rings and trapeze bars